FIGS. 1 illustrates an apparatus 10 which is disclosed in the Assignee's U.S. Pat. No. 5,275,484 which is incorporated herein by this reference in its entirety. The apparatus 10 continually processes liquids and/or solids (materials) including mixing, drying or reacting. A chamber 12 is used for processing of materials. The chamber 12 is comprised of a plurality of zones 14, 16, 18 which may be varied in number and dimension depending upon the particular application and the degree of processing required. The apparatus is supported by a stand 19. The zones 14, 16, 18 are defined by an inner wall 20 of the chamber 12 and weir 22 which is disposed at a boundary between zones within the chamber. An opening 24 extends vertically upward from the weir 22 between adjacent zones within the chamber 12 for permitting the materials to pass from one zone to an adjacent zone. The opening may be produced by a manually adjustable gate 26 which slides horizontally to permit adjustment of the opening 24. A shaft 32 is driven by a motor and gear box (prime mover) 34 for rotating a series of elements 36 which are connected to the shaft by radially extending members 38. The shaft 32 is rotatably supported by bearings 33. The elements 36 contact the material within the zones 14, 16, 18 to promote mixing, drying, and reacting, etc., of the materials within the zones. The elements 36 may have differing shapes promoting agitation, mixing, drying and reactions by moving material contacted by moving elements 36. The design, number and orientation of the mixing elements within each of the zones 14, 16, 18 is varied to control retention time of the matter within the zones. Contacting of the elements 36 with the materials within the zones controls the rate of movement of the material through the opening 24 between the zones and axially within a zone. Each of the elements 36 typically will have substantial surface area 37 which is inclined with respect to the axis of rotation of the shaft 32 to provide a plow-like function to move the material axially within the zone toward the opening 24.
Increasing of the rate of rotation of the shaft imparts additional energy to the materials within each of the zones 14, 16, 18 which increases the rate of movement of the materials through the opening 24 between the zones and decreasing the rate of rotation Decreases the rate of movement of materials through the opening. Additionally, the opening 24 between adjacent zones may be adjusted to be larger to increase the rate of movement of materials through the opening and may be adjusted to be smaller to decrease the rate of movement of materials through the opening.
A programmed controller 40, having an electrical control and logic panel, which may be in the form of a programmed control logic, controls the operation of the various components in the system including the rate of rotation of the shaft 32 produced by the prime mover 34. The programmed controller 40 may be programmed to control a rate of rotating of the shaft by the prime mover 34 to produce programmed contact of the elements 36 with the materials within the zones 14, 16, 18, a programmed rate of movement of the materials through the opening 24 between the zones and axially within a zone and a programmed dwell time of materials within each zone. The controller is programmable to cause the prime mover 34 rotating the shaft 32 for a first time interval at a lower speed to provide a lower rate of movement of the materials through the opening 24 between zones 14, 16, 18, a longer dwell time of a processing of the materials within the zones and to rotate the shaft for a second time interval at a higher speed than the lower speed to provide a higher rate of movement of the materials through the opening between the zones and a shorter dwell time of processing of materials within the zone. Alternatively, the controller 40 is programmable to cause the prime mover to rotate the shaft at a set speed to provide a continuous rate of processing and movement of materials through the opening between zones. The controller 40 may be implemented in any programmable device including a microprocessor or other programmable analog or digital device. The controller 40 includes a memory (not illustrated) for storing a plurality of different programs used for processing different materials which provides the ability to choose stored programs to economically process diverse types of materials without substantial manual overhead, especially when the controller controls all of the variable elements within the apparatus as described below.
A material input 42 controls the flow of materials to be processed by the apparatus and controls the addition of the materials into the first zone 14 and a material output 44 controls the flow of materials which has been finally processed in the final processing zone 18 from the apparatus. Both the material input and the material output 42 and 44 are atmospherically sealed to the chamber 12 with seals (not illustrated) so that non-atmospheric conditions may be provided within the material input, the material output and inside of the chamber during processing. A non-atmospheric pressure source 45 is coupled to the interior of the chamber 12 at one or more of the zones 14, 16, 18 or to the material input 42 or material output 44 to provide either a vacuum to promote drying and the removal of other vapors within the materials being processed or pressurization with gas used for processing materials within the chamber such as during chemical reactions within the chamber. The material input 42 and the material output 44 are provided with valuing to control the addition of materials for processing within the chamber and the removal of processed materials from the chamber while maintaining non-atmospheric pressure. The valving in the material input 42 and the material output 44 may be a pair of valves 46 and 48 which are connected in series in conduit within the material input 42 and the material output 44.
The valves 46 and 48 may be of diverse form including, but not limited to, slide gate valves as illustrated or ball or butterfly valves, etc. In order to control the pressure within the chamber 12 at non-atmospheric pressure, the valves 46 and 48 are operated under the control of the controller 40 to control movement of the materials through the material input 42 into the first zone 14.
The lower valve 48 in the material input 42 is controlled by the controller 40 to be closed while the upper valve 46 is controlled by the controller 40 to be open to seal the chamber 12 from atmospheric pressure and the hopper 106 during conveying of materials by the material input for addition to the first zone 14. Thereafter, the upper valve 48 is closed by the controller 40 to seal the materials conveyed by the material input from atmospheric pressure between the upper and lower valves. Finally, the lower valve 48 is opened by the controller 40 to cause the materials between the lower and upper valves to be added to the first zone 14. The above-described sequence of operation of the valves in the material output 42 is repeated cyclically during the continuous processing performed by the invention.
The lower valve 48 in the material input 44 is controlled by the controller 40 to be closed while the upper valve 46 in the material output is opened during discharge of materials from the last zone 18. Thereafter, the upper valve 46 in the material output 44 is closed by the controller 40 to seal the discharged materials between the valves from atmospheric pressure. Finally, the lower valve 48 is opened to cause the materials between the lower and upper valves 46 and 48 of the material output 44 to be moved between the valves typically by the effect of gravity. The above-described sequence of operation of the valves in the material output 44 is repeated cyclically during the continuous processing produced by the present invention. Vacuum, pressure or vibrating devices can be added to aid in the charging or discharging of the valves.
The material input 42 may contain miscellaneous processing equipment 51 such as, but not limited to, an agglomerating device for spraying liquid into powder introduced into hopper 106 to produce agglomeration of the powder or a high intensity agitator for purposes of predispersion of minor ingredients prior to introduction into the first zone 14 of the chamber 12. FIG. 6 described below illustrates an agglomerating device which may be disposed within the material input 42.
The chamber 12 contains the following additional structures. A removable lid 56 is mounted in the top section of the chamber 12 to permit access to each of the zones 14, 16, 18 including adjustment of the openings 24. A filtration screen may be disposed in one or more of the zones 14, 16, 18 in either the bottom or in the side of the chamber 12 for permitting liquid separation of liquids and solids disposed within the zones by liquid flowing through the screen outside the chamber. The filtration screen is periodically back-flushed during operation to prevent accumulation of excessive solids from occluding (blinding) the screen which would interfere with draining of liquid from the chamber when the invention is being used to filtrate materials containing undesired liquid components through the filtration screen. Viewing ports 60 may be disposed in the side walls of the chamber 12 to permit visualization of the processing within the chamber 12. Additionally, spray balls 62 may be installed to permit cleaning of the interior of the chamber 12 between processings.
A jacket may be provided in contact with the inner wall 20 of the chamber 12 and/or a jacket in contact with the weir(s) 22 and/or a hollow shaft 32 (not illustrated) for receiving cooling or heating fluids for controlling the temperature within the chamber for a suitable fluid source (not illustrated). A plurality of fluid ports are provided for coupling fluid to the jacket and outputting fluid from the jacket from the fluid source. Heated fluid may be coupled to the jacket to heat the chamber 12 to promote drying of product which is typically conducted under sub-atmospheric pressure. Cooling fluid may be coupled to the jacket to cool the chamber 12 to absorb heat generated by exothermic chemical reactions taking place within the zones 14, 16, 18. Diverse types of heating and cooling fluids may be utilized in conjunction with the jacket to provide precise control of temperature conditions within the chamber 12. For example, the jacket may be sectorized (not illustrated) such that each processing zone 14, 16, 18 is thermally coupled to a single jacket which receives fluid having the required temperature for processing the materials within the processing zone coupled to the jacket sector. Other means of introducing heating, such as gasses, infrared or microwave (not illustrated) may be used for thermal treatment.
The material output 44 may include an agitator disposed within the final zone 18 for contacting the material to cause the material to flow into the material output. The agitator may include an eccentric 112 mounted on the shaft 32. A member 114 is connected to the eccentric which extends into the material output 44 with rotation of the eccentric causing the member to reciprocate within the material output. As a result, any tendency of a finally processed solid to agglomerate or bridge is reduced to provide a uniform flow rate of finally processed material from the material output 44. Vibrators or air pads may also be used in the material movement through the input and output devices 42 and 44.
FIG. 2 illustrates a perspective view of a prior art multipurpose mixer which is disclosed in the Assignee's U.S. Pat. No. 4,705,222 which is incorporated herein by reference in its entirety. The apparatus 10' is positioned in an angular orientation for performing a specific mixing operation. The main parts of the apparatus 10' are a drum assembly 12', including a driven main axial drive shaft (not illustrated), a main housing 14', a detent pin mechanism 17' for locking the drum in any one of a plurality of angular positions. A support stand 16' is provided which supports the axis of rotation 17' of the driving assembly 12'. A control panel 18' contains controls for activating and controlling the speed of two motor drives and an ammeter used for monitoring the current draw by the motor which drives the main drive shaft located axially within the drum assembly 12. Preferably the motor for driving the main driven shaft is of variable speed with at least two selectable speeds to permit the drive shaft to be driven at speeds designed for diverse types of mixing operations as described below. The second motor drive 20' extends through the outside wall of the drum assembly orthogonally into the chamber formed by the drum for driving a high sheer deagglomerating impeller. The drum has a first end 22' which is removable from cylindrical section 23'. A clamp 24' is attached to the outside cylindrical section 23' and the first end 22' of the drum assembly 12' to lock the first end in place during operation. The clamp 24' also locks the drum assembly 12' to the main housing 14'. The part of the clamp 24' which clamps the first end of the drum in place is openable to permit the first end to be removed to place missing element assemblies on the main drive shaft. The first end 22' of the drum assembly 12' includes a port 26' which is located near the periphery of the first end at a position offset from the centrally disposed drive shaft. The port 26' includes a hollow cylindrical section 28' which has a first end which communicates with the interior of the drum assembly 12' and a second end having a closure 30' which is removable to permit materials to be placed inside of and removed from the drum assembly 14'. Typically, the materials are added to the drum while it is in its "vertical up" position and removed when it is in its "vertical down" position. The closure 30' is held in place by a clamp 32'. A plurality of holes 42' are drilled in the side panel of the main housing 14' or receiving the detent pin assembly 30' mounted in the upright portion of the support stand 16'. The controls for the motor drives are conventional.
FIG. 3 illustrates a sectional view of the apparatus of FIG. 2 used in the horizontal mixing mode. The drive shaft 46' is driven by a variable speed motor 48' which is controlled from the control panel 18'. The drive shaft 46' is rotatably supported in the second end 50' of the drum assembly 12' by a bearing 52'. A seal 54' is provided for preventing the bearing 52' from being contacted by materials being mixed within the drum assembly 12'. The drive shaft 46' has an extension 56' which is coupled to the variable speed motor 48' to couple rotary motion to the mixing elements 56' which are attached at spaced apart locations to a hollow cylindrical sleeve 58' which has an inner surface which contacts the outer surface of the drive shaft 46'. A hole 60' is diametrically drilled through the cylindrical sleeve 58' and the drive shaft 46' for receiving a pin (not illustrated) for locking the cylindrical sleeve 58' which drives the mixing elements 56' to the drive shaft 46'. Preferably, the mixing elements 56' are plow-shaped elements of well-known construction. The cylindrical section 23' is of double walled construction to form a jacket 61' useful for applications requiring heating or cooling. The port 61" is coupled to a suitable heat or cooling source to control the temperature of the mixing chamber. Each element 56' contains at least one sloped surface 62' which is inclined upward toward the drive shaft 46' to impart lift to materials being contacted by rotation of the mixing element. The individual mixing elements 56' are attached to the hollow cylindrical sleeve 58' by radial arms 64'. The arm 64' located closest to the second end 50' of the drum assembly 12' has a 90.degree. bend to permit the attachment point to the hollow cylindrical sleeve 58' to be axially offset from the position of the mixing element within the drum assembly 12'. The remaining three arms 64' are straight. The end of the drive shaft 46' is offset slightly from the first end 22' of the drum assembly. A deagglomerating impeller 68' projects orthogonally inward from the inner wall of the drum assembly 12' at a point midway between the first end 22' and the second end 50'. The deagglomerating impeller 68' includes a blade assembly 72' which is attached to a drive shaft 74' which is coupled to a motor 20'. The deagglomerating impeller drive shaft 74' is sealed against leakage by a sealing assembly 76'. The deagglomerating impeller 68' is used to control particle size of materials being mixed within the drum assembly 12' and to disperse any liquids. While the present invention is preferably used to perform horizontal mixing with the mixing element assembly as illustrated, it should be understood that other mixing element assemblies may be used which are designed for mixing particular materials or performing particular types of mixing actions while the drive shaft 46' is in the horizontal position.
U.S. Pat. No. 5,261,746 discloses a method of transporting and blending slurries in a sealed chamber with an oscillating paddle system. The system of the '746 Patent is used in conjunction with viscous slurries such as mash comprised of insolubles carried in a liquid. A driven shaft which rotates about a horizontal axis oscillates through a limited degree of rotation in order to lift the fluid mass from confining ends of the chamber to the center portion of the container. The paddles are offset by 90.degree. so that lifting of the fluid mass at opposite sides of the container occurs upon rotation of the shaft in alternate directions. Rotation in each direction between 90.degree. to 360.degree. is described. The liquid content of the chamber is not varied during rotation.
Most mixers, filters, dryers and chemical reactors utilize rotary motion inside of a cylindrical vessel which is either positioned vertically or horizontally. The use of rotary motion in these devices is complete rotary motion in which a mixing shaft is rotated in one direction to which are attached one or mixing elements which are typically rotated at either relatively slow or fast speeds.
Rotary motion in one direction in mixing devices is typified by several problems. The mixing action is typically so intense that it can change the particle size of the product mixed. During washing and filtration, the complete rotary motion can stir a slurry too fast making it harder to disengage during the filtration mode.
During drying of some products, the material changes from a liquid phase typically in the form of a slurry to a very viscous doughy phase which causes the product to form spaghetti-like strings that wrap around and stick to the drive shaft. The drying cycle is either stopped or substantially slowed because of inadequate contact with a heat and/or vacuum source. Large agglomerates and heavy buildup around the drive shaft inhibit further processing. These problems can occur when the assignee's aforementioned patents are utilized to perform drying operations in which the drive shaft is disposed in a nonvertical mode.
Additionally, certain types of substances which require a gentle mixing, coating or drying are damaged by contact caused by the mixing elements rotating at high speed in devices which use one-way rotation of driven shaft, such as the prior art apparatuses described above in conjunction with FIGS. 1-3.